Automotive vehicles are commonly equipped with audio radios for receiving broadcast radio frequency (RF) signals, processing the RF signals, and broadcasting audio information to passengers in the vehicle. More recently, satellite digital audio radio (SDAR) services have become available. SDAR services offer digital radio service covering a large geographic area, such as North America. Satellite-based digital audio radio services are available in North America, which generally employ either geo-stationary orbit satellites or highly elliptical orbit satellites that receive uplinked programming which, in turn, is rebroadcast directly to digital radios in vehicles on the ground that subscribe to the service. These systems also use terrestrial repeater networks in urban areas to supplement the availability of service. Each vehicle subscribing to the digital service generally includes a digital radio having a receiver and one or more antennas for receiving the digital broadcast.
The radio receivers are programmed to receive and unscramble the digital data signals, which typically include many channels of digital audio. In addition to broadcasting the encoded digital quality audio signals, the satellite-based digital audio radio service may also transmit data within a data bandwidth that may be used for various applications. The broadcast signal may also include other information for reasons such as advertising, informing the driver of warranty issues, providing information about the broadcast audio information, and providing news, sports, and entertainment broadcasting. Accordingly, the digital broadcast may be employed for any of a number of satellite audio radio, satellite television, satellite Internet, and various other consumer services.
In current satellite-based digital audio radio services, the same data stream is generally broadcast to all users of the service over a large geographic area covering multiple cities, states and countries. With the adoption of the consumer services broadcast, the ability to acquire local (i.e. regional) information such as local news, weather, traffic information, and the like has become problematic. For example, a gap exists in the ability of a national service provider to optimally supply local content (i.e. a region-wide broadcast), and, conversely, a gap exists in the ability of a local service provider to optimally supply national content (i.e. a nation-wide broadcast). Each local and national provider contains information that the user wants, however, each provider differs in broadcast channels (i.e. frequency modulation and coverage area). Even further, each provider differs in broadcast time. For example, news and weather may be broadcast at different times in an unsynchronized system; in this case, to switch from one broadcast source to the other may cause the end user to experience an abrupt change (i.e. the user may be listening to a song from a national broadcast and the system abruptly switches over to a local news update in the middle of a song. This of course undesirably detracts from the user listening experience.
To enable more subscribers to national broadcast systems without undesirable interruptions, a method is needed to give the end user local information without sacrificing bandwidth (i.e. the amount of broadcast data that is used by the largest number of potential users). Because each system has a fixed amount of broadcast data (number of bits), it is desired to maximize the efficiency of the data (i.e. bandwidth). For the national provider to supply local content (for many locations), the national provider would be using bandwidth that is only applicable to a smaller number of users in a region-specific area (i.e. the national broadcaster would have to allocate local programming content in their data stream for east coast, mid-west, and west-coast cities).
The associated problem occurs with the amount of bandwidth available to the national broadcaster, which essentially results in less data available for national use. To support many local broadcasts, the national service provider would have to eliminate national programs to accommodate the extra bandwidth for local content. Accordingly, the national broadcaster either loses programming content, which may result in the availability of fewer national programs or lost advertising time. In view of this, the local broadcaster, conversely, cannot compete with the national broadcaster on the amount of content that can be provided (i.e. the national broadcaster has a bandwidth advantage such that the national broadcaster may send 100 channels of various programming content, whereas the local broadcaster may be limited to 1 channel). Therefore, because the national system targets listeners for subscriptions, potential advertising revenue may be lost if there isn't a need to buy the subscription service if diverse programming transmitted over a large number of channels are not available, such that the national content is not undesirably interrupted with typically free local content.
Accordingly, it is therefore desirable to optimize the local and national method of broadcast for bandwidth and programming content for revenue stream such that service providers may acquire as many listeners as possible for their programming content (i.e. data bandwidth). In particular, it is desirable to provide the maximum amount of national content, such that the national content data is not diluted with local information, while also allowing the local content provider to provide local information. It is also desirable to allow the local provider a tie in to the national broadcaster such that the local provider obtains listener time even though the primary content is subscription content provided by the national provider.